Institut Francais Du Pe'trole

Rene Avrillon

Eric Robert

Jean-Claude Mileo

Daniel Defives

Andre Deschamps

Alain Driancourt

Andre Descamps

Alain Driancort

A highly selective asymmetric membrane for gas separation is provided which comprises rigid aromatic polyimide or copolyimide polymers comprising the monomers diphenyldi(trifluoromethyl)methane 3,4,3',4'-tetracarboxylic acid adianhydride and a monoaromatic metadiamine or a mixture of monoaromatic metadiamines.

Highly selective asymmetric membranes for gas separation

A method for preparing highly selective asymmetric polymer membranes for gas separation is provided wherein the polymer is dissolved in a volatile solvent containing dioxane, and a film or tube extrusion of the polymer solution is formed. Some of the solvent is evaporated and the film or tube is contacted with a coagulant comprising acetic acid and water. The film or the tube is then dried.

Highly selective asymmetric membranes for gas separation and method for

A gas separation membrane, comprising a film with a thickness ranging from 0.05-10.sup.-6 to 20.10.sup.-6 m, at least 90% by mole of which is at least one aromatic polyimide or copolyimide, the recurrent unit of which corresponds to the following formula (I): ##STR1## where A represents a tetravalent aromatic radical or a mixture of tetravalent aromatic radicals, and

Gas separation membrane

Disclosed is a gas separation membrane, comprising a film with a thickness ranging from 0.05.10.sup.-6 to 20.10.sup.-6 m, at least 90% by mole of which is at least one aromatic polyimide or copolyimide, the recurrent unit of which corresponds to the following formula (I): ##STR1## where A represents a tetravalent aromatic radical at least 50% by mole of which are represented by the following formula (II): ##STR2## and B represents a bivalent aromatic radical or a mixture of bivalent aromatic radicals.

A hydrocarbon cut is purified by contact with a solid adsorption resin consisting of a porous polycondensate or cross-linked copolymer comprising pyridyl or hydroxy groups and having pores essentially in the range of 6 to 300 Angstroms.

Process for purifying hydrocarbons by adsorption

Used lubricating oil is contacted with particles of a solid adsorption resin comprising at least 0.1 cc per gram of pores of diameter in the range of 6 to 300 angstroms. The resin is preferably a porous polycondensate or cross-linked copolymer comprising pyridyl or hydroxy groups, for example a polycondensate of phenol and formaldehyde. The resin may be reactivated by rinsing with an organic solvent such as an alcohol, a ketone or a chlorinated hydrocarbon.

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Maison Laffite, France

Rene Avrillon